This invention relates generally to a prosthetic total hip joint replacement system, and more specifically, to a modular hip prosthesis having modular components.
A natural hip joint may undergo degenerative changes due to a variety of etiologies. When these degenerative changes become so far advanced and irreversible, it may ultimately become necessary to replace the natural hip joint with a prosthetic hip. When implantation of such a hip joint prosthesis becomes necessary, the head of the natural femur is first resected and then a cavity is created within the intramedullary canal of the host femur for accepting and supporting the prosthetic hip.
Because different patients have femurs of various shapes, it is necessary to have available different appropriately structured prosthetic hip joint assemblies to accommodate these different shapes. Moreover, different patients having host femurs with substantially the same sized intramedullary canals may have femoral necks of different shapes and lengths and vice versa. Consequently, a prosthetic hip joint assembly that has a distal portion that is appropriate for one host femur may not have a metaphyseal portion which would provide the best fit for the femoral neck of that host femur. Accordingly, the most desirable fit may not always be possible, resulting in adverse affects on hip motion and patient comfort.
Different prosthetic hip joint assemblies have addressed this problem in the prior art. Of those, one includes a prosthetic hip joint assembly including a prosthesis body having a midsection portion and an upper neck portion adapted to carry an artificial femoral head. A plurality of tubular extension sleeves are adaptable to engage a stem portion of the midsection portion. The extension sleeves can be of varying lengths and curvatures such that an extension sleeve can be selected that will more aptly engage the intramedullary canal of a host femur. Additionally, specially configured pads can be attached to the midsection portion for increasing the cross-sectional shape of the body of the prosthesis to effectively engage the walls of the reamed cavity within the host femur.